On this machine the slot for the chart card opens directly into the inside of the unit, as far as I can tell, but the slot is only protected/waterproofed by a pathetic little rubber flap that is held in place by friction round its edges. (I have to say that I doubt that I would have bought the machine if I had been able to examine this arrangement before handing over my $ because it does seem a pretty pathetic solution)

Knowing the amount of saltwater I got over my last unit which had no card slot I just know that this new unit is not going to last 5 minutes unless I take steps to better protect the card slot. Does anyone have any suggestions about how best this might be achieved?

I am not too bothered about a pretty solution but it does need to be effective!

I was thinking about taping all round the edge of the unit - does anyone know of some seriously waterproof tape that will withstand a whole lot of water in the marine environment that I could use?

The only tape I came across that seems to protect the slot is silicone tape. I cut a full length that is unstretched that goes around the complete outside of the unit.

Remove the plastic sheet it comes on, hold one end against the edge and wrap the tape around the edge. Stretch the tape as you go and it seals on itself. I was able to wrap 3 times around .

Start the wrap at the lower corner and work around covering the bottom first. This will give you 3 wraps over the slot. I staggered the wraps a bit so they overlap and are not quite on top each other but form a wider area of coverage.

Silicone tape is great, leaves no residue behind, and easy to cut with a knife or scissors.

Another name for that tape is vulcanizing tape. We use it in the marine electronics world for weatherproofing antenna connections and other electrical connections that are exposed to the elements. One thing about it is that it's not very UV stable. We use the vulcanizing tape and then follow that up by wrapping the area in electrical tape to avoid the UV deterioration.

Another name for that tape is vulcanizing tape. We use it in the marine electronics world for weatherproofing antenna connections and other electrical connections that are exposed to the elements. One thing about it is that it's not very UV stable. We use the vulcanizing tape and then follow that up by wrapping the area in electrical tape to avoid the UV deterioration.

I forgot about the uv end of the tape. I will cover the area also with a good quality elec tape. Thanks

FYI I have just submitted feedback about the card slot & its flap to Lowrance via their website.

This may be a bit presumptuous because I haven't even used the unit yet - but I am not in a position to return it to the vendor and it is such an obvious design flaw that I would not even think about using it on my boat until I have found a way to properly seal up the slot against salt water ingress... because without doing so the unit is patently not going to last 5 minutes and all my $ will have been wasted.

Perhaps if enough owners of these devices do the same as me we will see better-designed products coming out in the future.

I would glob on the dialectric grease in and around the slot. Then insert card. It should act as a "gasket" in a sense. I would also do the tape wrap just to be sure!

I'd thought about the dialectric grease, but I fish quite a bit in the ocean with choppy conditions that blast the bottom of my finder. ...which leads me to another point, why put the card slot (or any slot) on the bottom. There's so much less of a chance for water getting in through the top.

personally I think that the bottom is not a bad place to put the slot - my FF frequently gets soaked from top to bottom as do I - if the hole was in the top any water finding its way onto the FF would naturally tend to flow into rather than out of the device.

My issue with the device is that calling it waterproof (IPX7) and marketing it as suitable for use on a kayak when the card slot is covered with such a pathetic little flap indicates that the designers have NO IDEA WHATSOEVER about the kind of conditions these machines will be used in to the point that I would describe this particular device as "not fit for purpose".

I should say that my assessment of the product is based on a physical examination in my living room not on any experience of using it - it is not even installed on my kayak yet.

The problem is that, given the cost of the device plus the cost of the chart I have bought to go in it, there is absolutely NO WAY I am going to take it out on my kayak until I have done something to remedy what I see as an obvious design flaw because I am 100% not confident that anybody is going to step up the plate and replace it (and/or chart installed in it) under a 2-year warranty if the machine has failed after getting the kind of dunking that I know it is going to get. If I go down that path I stand to lose all the money I have spent on it and it was just too expensive for me to risk that.

I have emailed my thoughts on these matters to the manufacturers whose response was a) it is certified as waterproof but that if I like I can use a bead of silicone round the edges to further seal the hole; b) if you don't like the product return it to the retailer; and c) the card slot is better protected on our larger and more expensive offering.

My reaction to the waterproofing certificate is that a lab test to prove waterproofing is not in any way the same as continual soaking and immersion throughout the life of the product in a live environment.

I bought mine online from a retailer in another country so I have no chance of returning it - otherwise I undoubtedly would have done so.

The advice to use a bead of silicone and that the next product up is more waterproof I take as a tacit recognition that they could have done better with the waterproofing on this product.

I suggested to them that I would be happy to test it for them in a live environment if they promised to replace it if it broke down due to water ingress but of course that offer elicited no response...

...so I have bought some of the tape recommended by others and have wrapped it up as best I can. I hope that this will do the trick but only time will tell.

Lowrance - if you are reading this - please take note that a "real world-waterproof" card slot is needed on any device you are going to sell for use on a kayak, irrespective of price but especially one which houses such an expensive electronic device. My suggestion is that this ought not to be too difficult to achieve: a simple screw cap with a seal ring or two would probably do the trick but a little floppy rubber flap simply does not cut the mustard and a push click hinged cover might look cool but it too, probably will not make a strong enough seal to withstand prolonged immersion (in the event that the kayak turns turtle in a shorebreak it might be many minutes before it gets righted) or keep out pressurised salt water (such as you meet when going out through a shorebreak).

I used electrical tape and Goop on top of that. This is on my 2nd Mark 4 DSI. The 1st didn't survive a huli in the surf (actually two hulis). Lowrance replaced the original under warranty.

The unit was not powered when it went under, and I didn't power it until two days later. Before I powered it up, I blew water out of the slot several times. When I powered it up, it came on normally for about 10 seconds, then flickered several times, and died.

I don't anticipate using the card slot, and hope to make it more or less permanently waterproof. I know one other guy I fish with had the exact same experience as I did.